Lathe tool



Aug. 18 1942- H. M. BEYREIS 2,293,680

LATHE TOOL Filed Jan. 30, 1942 7429@ JV. @eye/lf i Patented Aug. 18.11942 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as l amended April 30, 1928; 370 0. G. 757) 6 Claims.

The invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon,

The present invention relates to a lathe tool, and more particularly to a boring bar designed for internal cutting.

One of the principal objects .of the invention is to provide a lathe tool of peculiar construction and arrangement and particularly adapted to rigidly support a relatively small tool steel bit while cutting internal screw threads, etc.

A further object of the invention is to provide a novel and improved lathe tool including a boring bar having a c entral rod therein and so ar ranged that a tool steel cutting bit may be mounted at one end of the bar and clamped in position by clamping mechanism in an accessible position at the opposite end of the bar.

A further object of the invention is to provide a lathe tool including a cutting bit, boring bar, and bar mounting device, the boring bar and mounting being so designed and constructed as to cooperate with the tool holder of a lathe or similar machine to maintain the cutting tube in predetermined xed position.

A further object of the invention is to provide a boring bar having a substantially cylindrical body with a tapered end portion adapted to enter a drilled opening in the work, the tapered end of the boring bar being provided with a tool steel cutting bit adjustably clamped in position by clamping mechanism at the opposite end of the bar.

A further object of the invention is to provide a novel combination of boring bar and boring bar block mounting adapted to cooperate with each other to maintain the boring bar in xed position between clamping surfaces of the tool post of a lathe.

A further object of the invention is to provide a boring bar of generally cylindrical configuration including a smooth flat surface on one side thereof in combination with a rectangular mounting block arranged to encircle the cylindrical portions of .the surface of the bar and leave the hat portion thereof exposed, whereby it may be clamped into xed engagement with clamping surfaces of the lathe tool holder.

Referring now more particularly to the draw- Fig. 1 is a side elevation of a lathe tool assembly constructed in accordance with the teachings of the present disclosure.

Fig. 2 is a central sectional view of the tool 55 illustrated in Fig. 1, showing the several parts thereof in their operative relationship with the clamping surfaces of the tool holder of a lathe.

Fig. 3 is an end elevational view. The lathevtool consists of a boring bar II of generally cylindrical shape but including a atfaced surface I2 along one of its sides and having a tapered portion I3 terminating in a reduced diameter end portion Il.

A transverse square socket I5 is provided adjacent the small end I4 of the boring bar and the socket I5 is. arranged to receive a, hardened tool steel cutting bit I6.

The bit I6 is approximately square in crosssection, and is arranged to t closely within the socket i5. Its projection from the socket may be adjusted by advancing it from or withdrawing it into the socket of the boring bar.

'I'he bit I8 is rigidly clamped into position within the socket by means of a longitudinal clamping rod I1, which is arranged to extend through a cylindrical bore I8 of the boring bar to a point adjacent the opposite end of the bar. The central bore I8 is counter-bored at the end of the bar opposite the bit I6 and is threaded at I0 to receive the screw-threaded shank 2| of a thumbscrew 22. The screw head is knurled to facilitate tightening by hand, but it is also provided with a drilled opening 23 so that a tool may be inserted to increase the clamping action of the screw. It will be understood, of course, that in operation the bit I6 isrigidly clamped in position by tightening the knurled thumbscrew 22 since this action cause the end of the screw-threaded portion 2l of the screw to force the clamping rod I1 into rm engagement with the bit.

The boring bar II is arranged to be supported in a substantially rectangular mounting block 25 having a cavity 26 provided therein to receive the boring bar. vIt will be noted that the cavity 26 is of cylindrical shape and of proper size to snugly t the boring bar, It is not centrally located in the block 25, but is so positioned that one side of the boring bar II is exposedicn the side of the mountingpblock, in order that the flat-faced surface I2 of the boring bar may be placed in firm engagement against the surface of the tool mounting structure of a 1athe;` for` example, the surface indicated by the numeral 21.

It should be pointed out at this time that the tool mounting structures, such as vthe surface 21,

and the surface 28 cooperating therewith (and the surfaces 35 and 36 hereinafter described), are illustrated as representative of any types 0f tool clamping, arrangements commonly used in the machine tool'art, and have been illustrated in their present form only for purposes of convenience in the description of the invention. It should be understood that these surfaces may take any one of various forms and may consist of two parallel clamping surfaces, as illustrated, or may be set-screws, wedges, or other devices commonly used in the art. Inasmuch as the surfaces of the clamping mechanism or tool holder form a part of any one of several well known types of machines and do not form a part of the present invention except in combination with the other structure illustrated, they will not be shown in greater detailin this application.

It should be carefully noted that the shape and relationship of the tool holder and mounting block are such that the fiat surface I2 of the tool holder projects slightly from the plane of the flat surface 3| of the mounting block, so that when the assembly of boring bar and mounting block are clamped in the tool holder of the lathe the bar itself will be held in firm relationship with the tool holder and will thus effectively resist any tendency to shift responsive to forces incident to the operation of the tool. 'Ihe provision of the flat side I2 on the boring bar Il also makes it possible to utilize a relatively large boring bar in a tool post of standard width, to afford greater rigidity to the mounting for the cutting bit. It should also be noted that the tool holder or mounting block 25 is relieved at the point 32 so that the clamping force exerted between the surfaces 21 and 28 will be concentrated at the ends 33 and 34 of the mounting block, and, of course, at corre# sponding points with respect to the boring bar Il. 'Ihis construction provides, in effect, a twopoint suspension of the boring bar with the points 33 and 34 spaced apart from each other a distance suiilcient to give great rigidity to the mounting bar and enabling the operator to take relatively heavy cuts of metal without danger of shifting or chattering of the tool.

The mounting block 25 is also arranged to exert an additional clamping action in response to forces applied by setscrews or other clamping means above and below the mounting block at the points 35 and 36.` In this connection, it will be noted that the mounting block 25 includes a relatively thin structure at the point 31 adjacent the cavity 26 and when vertical pressure is applied to the surfaces of the mounting block the thin portion 31 will flex suficiently so that the entire interior cylindrical surface of the cavity 26 is clamped into rm engagement with the exterior surface of the boring bar. The lower surface of the mounting block 25 is relieved to concentrate the eiiective clamping action of the device at the opposite ends corresponding to the finished surfaces 38 and 39, and thus add to the rigidity of the mounting.

From the foregoing, it will be apparent that by followingr the teachings of the present disclosure, it is possible to provide a novel and improved lathe tool including improved means for adjustably securing a cutting bit at the remote end of a boring bar, and a novel mounting arrangement for the; Aboring bar arranged to give maximum rigidity, to prevent chattering, and provide maximum operating eiiiciency, while at the same time maintaining the advantages of an easily adjustable structure that may be easily and quickly applied to or recylindrical boring bar,

Patent is:

ofa relatively long cylindrical bar having a relativelyat surface on one side thereof, a transverse socket in said ba'r adjacent one end thereof, a central longitool socket, and a longitudinal clamping rod extending between ,the screw-threaded clamping screw and the tool socket and adapted to clamp a cutting bit in the sively to the force exerted screw; in combination with comprising a substantially having a semi-cylindricall cavity'` extending therethrough, said cavity being of a size to snugly engage the exterior surfaces of the boring bar by the clamping molmting means and intersecting one of the fiat surfaces ofthe mounting block in such a manner that the fiat surface of the boring bar will project beyond the fiat surface of the mounting block to the end that when said mounting block and bar are clamped between cooperating clamping surfaces a clamping force will be exterted directly'on the flat surfaces of theboring bar.

2. A boring bar consisting of a relatively long the said boring har-including a relatively at surface on one side thereof; in combination with a mounting block comprising a substantially rectangular block having a semi-cylindrical cavityl extending therethrough, said cavity being of 'a size to snugly engage the exterior surfaces of the boring bar and intersecting one of the fiat surfaces of the mounting`- block in such a manner that the flat surface of the boring bar will project beyond the flat surface of the mounting block to the end that when said mounting block and bar are clamped between cooperating clamping surfaces a clamping force will be exerted directly on the flat surfaces of the boring bar.,

3. A boring bar consisting of a relativeiylong cylindrical boring bar, the said boring bar including a relatively fiat surface on one side thereof; in combination with a mounting block comprising a substantially rectangular block having a semi-cylindrical cavity extending therethrough, said cavity being exterior surfaces of the boring bar and intersecting one of the fiat surfaces of the mounting block in such a manner that the flat surface of the boring bar will project beyond the flat surface of the mounting block to the end thatwhen said mounting block and bar are clamped between cooperating clamping surfaces a clamping force will be exerted directly on the fiat surfaces of the boxing bar, said mounting block also including a relatively thin area adiacent the the cylindrical surfaces of the block cavity to be urged into clamping relationship against the exterior cylindrical surface of the boring bar.

toolsocketrpon-- rectnsllllr block of a size to snugly engage thev sively to the force exerted by the clamping screw; Y

the said boring bar including a relatively ilat exterior surface on one side thereof, adapted to cooperate with and be clamped in dat face-to-face relation with a mounting block to secure the bar in xed position.

5. A boring bar consisting of a relatively long cylindrical bar having a tapered end portion terminating in a reduced cutting end, a transverse socket in said bar adjacent the reduced end, a central longitudinal bore extending through said bar, a screw-threaded clamping element longitudinally extending into said bar at the end opposite the tool socket, and a longitudinal clamping rod extending between the screw-threaded clamping screw and the tool socket and adapted to clamp a cutting bit in the tool socket responsively to the force exerted by the clamping screw in combination with a mounting block comprising a substantially rectangular block having a semicylindrical cavity extending therethrough, said cavity being of a size to snugly engage the exterior surfaces of the boring bar and intersecting to one surface of the mounting block, said mounting block including a relatively thin area adiacent the cylindrical cavity whereby minute flexing responsive to clamping action exerted on the opposite surfaces of the block will cause the cylindrical surfaces of the blockcavity to be urged into clamping relationship against the exterior lcylindrical surfaces of the boring bar.

6. A boring bar consisting of a relatively lon cylindrical bar having a relatively fiat surface on one side thereof and a tapered end portion terminating in a reduced cutting end, a transverse socket in said bar adjacent the reduced end, a central longitudinal bore extending through said bar, a screw-threaded clamping element longitudinally extending into said bar at the end opposite the tool socket. and a longitudinal clamping rod extending between the screw-threaded clamping screw and the tool socket and adapted' to clamp a cutting bit in the tool socket responsively to the force exerted by the clamping screw;l in combination with mounting means comprising a substantially rectangular block having a semi-cylindrical cavity extending therethrough, said cavity being of a size to snugly engage the exterior surfaces of the boring bar and fintersecting one of the iiat surfaces of the mounting block in such a manner that the at surface of the boring bar will project beyond the flat sur face of the mounting block, to the end that when said mounting block and bar are clamped between cooperating clamping surfaces, a clamping force will be exerted directly on the at surfaces of the boring bar; said mounting block also including a relatively thin area adjacent the cy- 'lindrical surfaces of the boring bar.

lindrical cavity whereby minute flexing responsive to clamping action exerted on the opposite surfaces of the block will cause the cylindrical surfaces of the block cavity to be urged into clamping relationship against the exterior cy- HENRY M. BEYREIS. 

